1. Field of the Invention
The present invention relates to base stations used in wireless communications, and more specifically to antennas supporting high density of users in specific directions.
2. Related Art
An antenna generally refers to a component which is used to send and receive wireless signals. In a typical configuration, the antenna is contained in a base station which transmits and receives voice, data, video, etc., in the form of electromagnetic waves. The base station enables wireless users (or wireless devices, in general) to communicate with various other (mobile devices) users, as is well known in the relevant arts.
Base stations are often employed to ensure that the areas (or users within that area) sought to be covered are within the range of wireless signals transmitted by the corresponding antennas. A wireless signal is generally characterized by illumination (energy intensity) at each point of the covered area, and a threshold level of illumination is generally necessary for coverage to extend to the corresponding point. In addition, higher illumination leads to better signal-to-noise-ratio (SNR), which in turn lead to advantages such as high data transfer rates.
A prior base station may provide for a hemispherical coverage area, with approximately uniform illumination in each segment of the area. Such an approach ensures that users at any portion of the hemispherical area are consistently provided connectivity. However, such a solution may not be suitable in areas where users are present in only small portions of the coverage area (e.g., in rural areas) since electrical power is wasted illuminating portions of the covered area in which users are not present. The antennas used in such base stations are generally referred to as ‘normal antennas’ (as opposed to smart antennas described below).
Another prior base station may overcome some of such disadvantages by using a ‘smart antenna’. Such base stations generally operate by ‘learning’ the specific direction in which active users are present, and beaming (transmitting) only in the directions in which such users are present. The direction of beaming is often controlled by controlling the phase of the signals emitted by each antenna element (contained in the antenna). By transmitting only in the directions in which active users are present, unneeded wastage of power may be avoided. Thus, smart antennas are generally suitable in coverage areas having low density of subscribers.
One problem with smart antenna-based base stations is that the required electronic circuitry (e.g., to control the antenna elements) may be complex, expensive and/or subject to a poor performance due to manufacturing imperfections, particularly as the base stations working at millimeter wave bands needs to support higher transfer rates.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.